California Psychological Inventory (CPI) for Police Selection

Overview

The California Psychological Inventory (CPI) is a selfreport inventory designed to assess normal personality traits and interpersonal styles in adolescents and adults. Developed by Harrison G. Gough in the 1950s, the CPI has been widely used in research, counseling, and selection contexts, including lawenforcement agencies that seek a scientifically based method for evaluating candidates.

Why Police Agencies Use the CPI

• Predictive validity: The CPIs scales have demonstrated modest but reliable relationships with job performance, especially in areas such as stress tolerance, judgment, and teamwork.
• Legal defensibility: Because the CPI is a standardized, psychometrically sound test, its results can be defended in court if a selection decision is challenged.
• Broad personality coverage: The instrument evaluates 20 primary scales (e.g., Dominance, Sociability, SelfControl) and 7 supplemental scales that together capture facets relevant to policing, such as aggression control and ethical orientation.
• Ease of administration: The CPI434 (the most common form) takes about 4560 minutes to complete and can be administered on paper or via computer.

Key CPI Scales Relevant to Law Enforcement

While all CPI scales provide useful information, the following are most frequently examined in police selection:

• SelfControl (S) Measures impulse regulation and emotional stability. Low scores may signal susceptibility to anger or risky behavior.
• Dominance (D) Reflects assertiveness and leadership potential. Extremely high scores can indicate a tendency toward dominanceovercollaboration, while very low scores may suggest passivity.
• Responsibility (R) Assesses dependability, conscientiousness, and adherence to rules.
• Socialization (S) Gauges respect for social norms and authority. Low scores have been linked to antisocial tendencies.
• Flexibility (F) Indicates openness to new ideas and adaptabilitycritical for problemsolving in dynamic environments.
• SelfAcceptance (SA) Reflects realistic selfevaluation and confidence without inflated ego.
• Empathy (E) Although not a primary CPI scale, several supplemental scales (e.g., Human Relations) tap empathy and interpersonal sensitivity, both vital for community policing.

Interpretation in a Police Context

Interpretation should be performed by a qualified psychologist trained in forensic assessment. The typical process includes:

1. Validity review: Check for inconsistent responding, random patterns, or extreme answering styles.
2. Profile analysis: Examine the pattern of primary scales to identify strengths (e.g., high Responsibility) and potential red flags (e.g., low SelfControl).
3. Composite scores: Some agencies use aggregated scores such as Police Suitability Index, which combines relevant scales with weighted formulas.
4. Comparison to norms: Scores are compared to the CPI standardization sample and, when available, to a policespecific normative group.
5. Report & feedback: Results are synthesized into a concise report that outlines predictive implications for the candidates ability to handle stress, make ethical decisions, and work with the public.

Strengths of the CPI for Police Selection

• Comprehensive personality picture: Captures both interpersonal and selfmanagement aspects.
• Empirically derived norms: Allows for objective comparison across candidates.
• Compatibility with other assessments: Frequently paired with cognitive ability tests, situational judgment tests (SJTs), and structured interviews for a multimethod approach.
• Low adverse impact: Research shows the CPI generally produces small differences across demographic groups, supporting equalopportunity hiring.

Limitations and Considerations

Despite its benefits, the CPI is not a standalone predictor of policing success. Key cautions include:

• Moderate predictive power: Correlations with actual police performance typically range from .20 to .35, indicating that personality is just one piece of the puzzle.
• Cultural relevance: Norms are based on U.S. samples; agencies serving diverse communities should ensure cultural fairness.
• Faking risk: Candidates motivated to appear ideal may inflate desirable traits; builtin validity scales help detect this, but they are not foolproof.
• Legal context: Use of any psychological test must comply with the Uniform Guidelines on Employee Selection Procedures (EEOC) and local regulations.

Best Practices for Implementation

To maximize the utility of the CPI, agencies should adopt the following protocol:

1. Job analysis: Clearly define the competencies required for the specific policing role (e.g., patrol officer vs. detective).
2. Validation study: Conduct a local validation by correlating CPI scores with performance metrics such as supervisor ratings, disciplinary records, and field evaluations.
3. Integrated selection system: Use the CPI alongside structured interviews, physical agility tests, and cognitive assessments.
4. Training for assessors: Ensure that psychologists and HR staff are trained in CPI administration, scoring, and forensic reporting.
5. Feedback loop: Periodically review selection outcomes to adjust weighting of CPI scales based on predictive accuracy.

Case Example: A MidSize Police Department

Cityville Police Department (population 200,000) introduced the CPI in 2019 as part of a revamped hiring system. After a 12month pilot, the department reported:

• A 15% reduction in earlycareer attrition, attributed to better matching of candidates selfcontrol and responsibility levels.
• Improved officerpublic interaction scores on citizen surveys, linked to higher empathy and socialization scores.
• No statistically significant increase in adverse impact for any protected class.

The department continues to calibrate the weighting of CPI scales based on ongoing performance data.

Conclusion

The California Psychological Inventory offers police agencies a reliable, researchbacked method for assessing personality traits that influence job performance, ethical conduct, and resilience under stress. When used responsiblypaired with other selection tools, validated for the specific agency, and interpreted by qualified professionalsthe CPI can enhance the quality of hires, promote fairness, and support the overall effectiveness of lawenforcement teams.

Further Reading

• Gough, H. G., & Bradley, P. (1996). California Psychological Inventory: Administration, Scoring, and Interpretation Manual. Consulting Psychologists Press.
• Roberts, B. W., & Jackson, J. J. (2008). "Continuities and discontinuities in the development of adult personality traits." Psychology and Aging, 23(5), 10751085.
• National Research Council. (2005). Science and Justice: A Framework for Forensic Science in the TwentyFirst Century. The National Academies Press.
• U.S. Equal Employment Opportunity Commission. (2022). Uniform Guidelines on Employee Selection Procedures.